U.S. patent application number 13/425507 was filed with the patent office on 2013-04-25 for self-adjusting photosensive touch circuit and display device thereof.
This patent application is currently assigned to AU OPTRONICS CORP.. The applicant listed for this patent is Yueh-Hung Chung, Ya-Ling Hsu. Invention is credited to Yueh-Hung Chung, Ya-Ling Hsu.
Application Number | 20130100077 13/425507 |
Document ID | / |
Family ID | 46187528 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130100077 |
Kind Code |
A1 |
Chung; Yueh-Hung ; et
al. |
April 25, 2013 |
SELF-ADJUSTING PHOTOSENSIVE TOUCH CIRCUIT AND DISPLAY DEVICE
THEREOF
Abstract
The present invention relates to a self-adjusting photosensitive
touch circuit, which includes a light-sensing component, a variable
capacitor and a switch component. The light-sensing component is
for sensing a touch status and receives a first control signal. The
light-sensing component is enabled by a level of the first control
signal. The variable capacitor is electrically coupled to the
light-sensing component. A capacitance of the variable capacitor is
altered along with a voltage difference between two terminals of
the variable capacitor. The switch component is electrically
coupled to the variable capacitor, and receives a second control
signal. The switch component is enabled by a level of the second
control signal. Therefore, a range of the gate voltage difference
of the light-sensing component can be increased, so as to improve
the sensitivity and accuracy of the light-sensing component.
Moreover, the present invention also relates to a display device
thereof.
Inventors: |
Chung; Yueh-Hung; (Hsin-Chu,
TW) ; Hsu; Ya-Ling; (Hsin-Chu, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chung; Yueh-Hung
Hsu; Ya-Ling |
Hsin-Chu
Hsin-Chu |
|
TW
TW |
|
|
Assignee: |
AU OPTRONICS CORP.
Hsin-Chu
TW
|
Family ID: |
46187528 |
Appl. No.: |
13/425507 |
Filed: |
March 21, 2012 |
Current U.S.
Class: |
345/175 |
Current CPC
Class: |
G06F 3/0416 20130101;
G06F 3/042 20130101 |
Class at
Publication: |
345/175 |
International
Class: |
G06F 3/042 20060101
G06F003/042 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2011 |
TW |
100138161 |
Claims
1. A self-adjusting photosensitive touch circuit comprising: a
light-sensing component, for sensing a touch status, and receiving
a first control signal, wherein the light-sensing component is
enabled by a level of the first control signal; a variable
capacitor, electrically coupled to the light-sensing component,
wherein a capacitance of the variable capacitor is altered along
with a voltage difference between two terminals of the variable
capacitor; and a switch component, electrically coupled to the
variable capacitor, and configured for receiving a second control
signal, wherein the switch component is enabled by a level of the
second control signal.
2. The circuit as claimed in claim 1, wherein light-sensing
component comprises a first terminal, a second terminal and a third
terminal, the first terminal thereof receives the first control
signal, the second terminal thereof is electrically coupled to the
variable capacitor, and the third terminal thereof receives a third
control signal.
3. The circuit as claimed in claim 2, wherein the variable
capacitor comprises a first terminal and a second terminal, the
first terminal thereof is electrically coupled to the second
terminal of the light-sensing component, and the second terminal
thereof receives a reference voltage.
4. The circuit as claimed in claim 3, wherein when the first
control signal is in the high level, the third control signal is in
the high level, and rising edges of the first control signal and
the third control signal are behind a rising edge of the second
control signal.
5. The circuit as claimed in claim 4, wherein when the second
control signal is in the high level, a voltage of the second
terminal of the variable capacitor increases to a first voltage
value; and when the second control signal is in the low level and
the first control signal and the third control signal are in the
high level, the voltage of the second terminal of the variable
capacitor increases to a second voltage value.
6. The circuit as claimed in claim 2, wherein the variable
capacitor comprises a first terminal and a second terminal, the
first terminal of the variable capacitor receives a reference
voltage, and the second terminal of the variable capacitor is
electrically coupled to the second terminal of the light-sensing
component.
7. The circuit as claimed in claim 6, wherein when the first
control signal is in the high level, the third control signal is in
the low level, falling edges of the first control signal and the
third control signal are behind a rising edge of the second control
signal.
8. The circuit as claimed in claim 7, wherein when the second
control signal is in the high level, a voltage of the first
terminal of the variable capacitor decreases to a first voltage
value; and when the second control signal and the third control
signal are in the low level and the first control signal is in the
high level, the voltage of the first terminal of the variable
capacitor decreases to a second voltage value.
9. The circuit as claimed in claim 2, wherein the switch component
comprises a first terminal, a second terminal, and a third
terminal, the first terminal thereof receives the second control
signal, and the second terminal thereof is electrically coupled to
the second terminal of the light-sensing component.
10. The circuit as claimed in claim 9, further comprising an
integrator, electrically coupled to the third terminal of the
switch component, to output a touch signal corresponding to the
touch status.
11. The circuit as claimed in claim 1, wherein when light
irradiation intensity received by the light-sensing component is
higher, the capacitance of the variable capacitor is greater.
12. A self-adjusting photosensitive touch display device,
comprising: at least one scanning line; at least one data line; a
plurality of display pixel units, electrically coupled to the
scanning line and the data line, respectively; and at least one
self-adjusting photosensitive touch circuit, comprising: a
light-sensing component, for sensing a touch status, and receiving
a first control signal, wherein the light-sensing component is
enabled by a level of the first control signal; a variable
capacitor, electrically coupled to the light-sensing component,
wherein a capacitance of the variable capacitor is altered along
with a voltage difference between two terminals of the variable
capacitor; and a switch component, electrically coupled to the
variable capacitor, and configured for receiving a second control
signal, wherein the switch component is enabled by a level of the
second control signal.
13. The display device as claimed in claim 12, wherein the
light-sensing component is a photoelectric thin film
transistor.
14. The display device as claimed in claim 12, wherein when light
irradiation intensity received by the light-sensing component is
higher, a capacitance of the variable capacitor is greater.
Description
TECHNICAL FIELD
[0001] The disclosure generally relates to a touch circuit and a
display device, and more particularly to a self-adjusting
photosensitive touch circuit and a display device thereof.
BACKGROUND
[0002] At present, touch panel technology generally includes
following several types: resistive type, capacitive type, optical
type, electromagnetic type, ultrasonic type, and in-cell type
liquid crystal panel (which includes resistive type, capacitive
type, and optical type). In a display device with an in-cell type
photosensitive touch panel, it uses leakage current differences
caused by different light irradiation intensity as a condition
whether turning on a light-sensing component in the in-cell type
photosensitive touch panel, so as to judge whether the in-cell type
photosensitive touch panel has been touched.
[0003] For example, the light-sensing component includes a thin
film transistor, and so on. When the light-sensing component is
touched by a finger, irradiated by ambient light, and touched by a
light pen, leakage currents of the thin film transistor are
corresponding to a first current value, a second current value, and
a third current value, respectively. Therefore, when the light
irradiation intensity received by the light-sensing component is
higher, the leakage current Ids of the thin film transistor is
greater, that is to say, the first current value is less than the
second current value, and the second current value is less than the
third current value. Then, a charge difference generated by the
different leakage currents of the thin film transistor is converted
into an output voltage by an integrator, so as to judge whether is
touched according to the value of the output voltage.
[0004] The above-mentioned judging process only employs one thin
film transistor as an example. However, a touch panel can includes
ten thousand light-sensing components, and current-voltage curves
of each thin film transistor in the touch panel may be different.
As shown in FIG. 1, a current-voltage curve of a first thin film
transistor TFTA is different from that of a second thin film
transistor TFTB. For example, in the conditions with light
irradiation and no light irradiation, a same gate voltage Vgs
(e.g., -3 volts), for the first film transistor TFTA, it can
effectively judge whether the first film transistor TFTA is
touched. However, for the second film transistor TFTB, a
misjudgment result may be generated. Therefore, based on difference
characteristics of the different thin film transistors, the
light-sensing component may generate misjudgment results.
SUMMARY OF EMBODIMENTS
[0005] Accordingly, the present disclosure relates to a
self-adjusting photosensitive touch circuit and a display device
thereof, which can use a variable capacitor which can adjust a
capacitance thereof, to increase a range of a gate voltage
difference of the light-sensing component and reduce the
misjudgment probability of the light-sensing component.
[0006] The present disclosure relates to a self-adjusting
photosensitive touch circuit, which includes a light-sensing
component, a variable capacitor, and a switch component. The
light-sensing component is for sensing a touch status, and receives
a first control signal. The light-sensing component is enabled by a
level of the first control signal. The variable capacitor is
electrically coupled to the light-sensing component. Capacitance of
the variable capacitor is altered along with a voltage difference
between two terminals of the variable capacitor. The switch
component is electrically coupled to the variable capacitor, and
receives a second control signal. The switch component is enabled
by a level of the second control signal.
[0007] The present disclosure also relates to a self-adjusting
photosensitive touch display device, which includes at least one
scanning line, at least one data line, a plurality of display pixel
units, and at least one self-adjusting photosensitive touch
circuit. The display pixel units are electrically coupled to the
scanning line and each of the data line, respectively. The
self-adjusting photosensitive touch circuit includes a
light-sensing component, a variable capacitor, and a switch
component. The light-sensing component is for sensing a touch
status, and receives a first control signal. The light-sensing
component is enabled by a level of the first control signal. The
variable capacitor is electrically coupled to the light-sensing
component. A capacitance of the variable capacitor is altered along
with a voltage difference between two terminals of the variable
capacitor. The switch component is electrically coupled to the
variable capacitor, and receives a second control signal. The
switch component is enabled by a level of the second control
signal.
[0008] In summary, the self-adjusting photosensitive touch circuit
and the display device of the present disclosure uses the
characteristics of the variable capacitor which can automatically
adjust the capacitance thereof. When there is no light irradiation
on the touch circuit, the variable capacitor automatically changes
to have a small capacitance, so that the stored charge is small.
When there is light irradiation on the touch circuit, the variable
capacitor changes to a large capacitance, so that the stored charge
is great, thereby making a charge difference between the light
irradiation condition and no light irradiation condition be
greater. In other words, the range of the gate voltage difference
of the light-sensing component can be increased, so as to improve
sensitivity and accuracy of the light-sensing component and the
touch display device thereof.
[0009] Other embodiments of the disclosure will be further
understood from the further technological features disclosed by the
embodiments of the present disclosure wherein there are shown and
described preferred embodiments, simply by way of illustration of
modes best suited to carry out the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The various embodiments disclosed herein will be better
understood with respect to the following description and drawings,
in which like numbers refer to like parts throughout, and in
which:
[0011] FIG. 1 is a current-voltage curve diagram of a thin film
transistor of a conventional technology;
[0012] FIG. 2 is a schematic view of a circuit in accordance with a
first exemplary embodiment of the present disclosure;
[0013] FIG. 3 is a timing-sequence view of signals of the first
exemplary embodiment of the present disclosure;
[0014] FIG. 4A is a curve diagram of an output voltage difference
and a gate voltage of a conventional technology;
[0015] FIG. 4B is a curve diagram of an output voltage difference
and a gate voltage of the first exemplary embodiment of the present
disclosure;
[0016] FIG. 5 is a schematic view of a circuit in accordance with a
second exemplary embodiment of the present disclosure;
[0017] FIG. 6 is a timing-sequence view of signals of the second
exemplary embodiment of the present disclosure;
[0018] FIG. 7A is another curve diagram of another output voltage
difference and a gate voltage of a conventional technology;
[0019] FIG. 7B is a curve diagram of an output voltage difference
and a gate voltage of the second exemplary embodiment of the
present disclosure;
[0020] FIG. 8 is a structure schematic view of a variable capacitor
in accordance with an exemplary embodiment of the present
disclosure; and
[0021] FIG. 9 is a partial circuit block diagram of a display
device in accordance with an exemplary embodiment of the present
disclosure.
DETAILED DESCRIPTION
[0022] FIG. 2 is a schematic view of a circuit in accordance with a
first exemplary embodiment of the present disclosure. Referring to
FIG. 2, a self-adjusting photosensitive touch circuit 100 in
accordance with the first exemplary embodiment of the present
disclosure includes a light-sensing component 10, a variable
capacitor 20, and a switch component 30.
[0023] The light-sensing component 10 is configured for sensing a
touch status corresponding to a user's operation. The light-sensing
component 10 may be a photoelectric thin film transistor. The
light-sensing component 10 can receive a first control signal Gn+1,
and the light-sensing component 10 is enabled by a level of the
first control signal Gn+1. For example, the high level of the first
control signal Gn+1 can make the light-sensing component 10 be
turned on. The light-sensing component 10 includes a first terminal
(e.g., a gate) 13, a second terminal (e.g., a drain) 15, and a
third terminal (e.g., a source) 17. The first terminal 13 receives
the first control signal Gn+1. The third terminal 17 receives a
third control signal Sn+1.
[0024] The variable capacitor 20 is electrically coupled to the
light-sensing component 10. In detail, the variable capacitor 20
includes a first terminal 23 and a second terminal 25. The first
terminal 23 is electrically coupled to the second terminal 15 of
the light-sensing component 10. The second terminal 25 receives a
reference voltage Vc1. The variable capacitor 20 can change its
capacitance along with a voltage difference between the first
terminal 23 and the second terminal 25. For example, when the
voltage difference between the first terminal 23 and the second
terminal 25 of the variable capacitor 20 is greater, the
capacitance of the variable capacitor 20 is less. In other words,
the voltage difference is inversely proportional to the capacitance
of the variable capacitor 20. The variable capacitor 20 may be a
metal insulator semiconductor (MIS) capacitor.
[0025] The switch component 30 is electrically coupled to the
variable capacitor 20. The switch component 30 receives a second
control signal Gn, and the switch component 30 is enabled by level
of the second control signal Gn. For example, the high level of the
second control signal Gn can make the switch component 30 be turned
on. The switch component 30 may be a MIS field effect transistor
switch, or a thin film transistor switch. The switch component 30
includes a first terminal (e.g., a gate) 33, second terminal (e.g.,
a drain) 35, and a third terminal (e.g., a source) 37. The first
terminal 33 receives the second control signal Gn. The second
terminal 37 is electrically coupled to the first terminal 23 of the
variable capacitor 20. The third terminal 37 is electrically
coupled to a data line (or is called a readout line). Therefore,
output voltage Vout can be provided to a next-stage circuit (not
shown).
[0026] FIG. 3 is a time-sequence view of signals of the first
exemplary embodiment of the present disclosure. Please referring to
FIG. 2 and FIG. 3 together, the following will describe the
operation principle of the self-adjusting photosensitive touch
circuit 100, and the operation process of the self-adjusting
photosensitive touch circuit 100 can be divided into a reading-out
stage, a resetting stage, and a sensing stage.
[0027] Firstly, in the reading-out stage, when the second control
signal Gn is in the high level, the switch component 30 is turned
on, the voltage Va0 of the first terminal 23 of the variable
capacitor 20 is increased to a first voltage value Va1 (or a
reference voltage Vref as shown in FIG. 9) with time.
[0028] In the resetting stage, when the first control signal Gn+1
and the third control signal Sn+1 are in the high level, and the
second control signal Gn is in the low level, the switch component
30 is turned off, the light-sensing component 10 is turned on, and
voltage Va0 is increased from the first voltage value Va1 to a
second voltage value Va2 with time. The second voltage value Va2 is
close to the voltage value of the third control signal Sn+1. In
addition, when the first control signal Gn+1 and the third control
signal Sn+1 are in the high level, rising edges of the first
control signal Gn+1 and the third control signal Sn+1 are behind a
rising edge of the second control signal Gn.
[0029] In the sensing stage, when the first control signal Gn+1 and
the third control signal Sn+1 is in the low level, and the second
control signal Gn is in the low level, the switch component 30 is
turned off and the light-sensing component 10 is turned off, the
gate voltage Vgs of the light-sensing component 10 is equal to a
value that the low level of the first control signal Gn+1 subtracts
the low level of the third control signal Sn+1. Thus, the voltage
Va0 decreases from the second voltage value Va2 with time.
[0030] Then, return back to the reading stage, when the second
control signal Gn is in the high level again, the switch component
30 is turned on, and the voltage Va0 of the first terminal 23 of
the variable capacitor 20 is increased again to the first voltage
value Va1 (or the reference voltage Vref) with time.
[0031] Therefore, when there is no light irradiation, the voltage
Va0 is increased to cause the voltage difference .DELTA.V to be
decreased, the capacitance of the variable capacitor 20 is
automatically decreased, so that the charge stored in the variable
capacitor 20 becomes less. The voltage difference .DELTA.V is equal
to a value that the reference voltage Vc1 subtracts the voltage
Va0. Then, when the second control signal Gn is in the high level
again, the integrator 150 (as shown in FIG. 9) judges the touch
state according to a relationship between the current voltage Va0
and the reference voltage Vref. In detail, in the reading-out
stage, when the voltage Va0 is not less than the reference voltage
Vref, it determines the touch status is no touch.
[0032] When the light irradiates with the high intensity, the
voltage Va0 is decreased to cause the voltage difference .DELTA.V
is increased, the capacitance of the variable capacitor 20 is
automatically increased, so that the charge stored in the variable
capacitor 20 becomes greater. Similarly, when the second control
signal Gn is in the high level again, the integrator 150 judges the
touch status according to a relationship between the current
voltage Va0 and the reference voltage Vref. In detail, in the
reading-out stage, when the voltage Va0 is less than the reference
voltage Vref and is equal to a preset voltage value, it determines
the touch status is having the touch. The reference voltage Vref is
greater than the preset voltage value. It should be noted that, the
judgment of the touch status in the embodiments of the preset
disclosure are only for examples, it is not used as constraint
conditions, and the judgment of the touch status mainly depends on
the structure or the setting value of a back-end detection circuit
(e.g., the integrator 150).
[0033] FIG. 4A is a curve diagram of the output voltage difference
and the gate voltage of a conventional technology. FIG. 4B is a
curve diagram of the output voltage difference and the gate voltage
of the first exemplary embodiment of the present disclosure.
Referring to FIG. 4A, the conventional technology uses a capacitor
with a fixed capacitance, the gate voltage Vgs of the light-sensing
component 10 is in a range from about -3.8 volts to 1.2 volts.
Referring to FIG. 4B, after using the variable capacitor 20 of the
first embodiment of the present disclosure, the gate voltage Vgs of
the light-sensing component 10 is in a range from about -3.5 volts
to 5.2 volts. Therefore, an operational range of the light-sensing
component 10 is approximately 3 times that of the light-sensing
component of the conventional technology. It should be noted that,
due to the operational range of the light-sensing component 10 of
the present disclosure being increased, it will increase the
misjudgment probability of the light-sensing component 10, and
improve relatively the sensitivity and accuracy of the
light-sensing component 10.
[0034] FIG. 5 is a schematic view of a circuit in accordance with a
second exemplary embodiment of the present disclosure. Referring to
FIG. 5, that the second embodiment is similar with the first
embodiment, except that the connection relationship of the variable
capacitor 20 in the second embodiment is opposite to the connection
relationship of the variable capacitor 20 in the first embodiment.
In detail, the first terminal 23 of the variable capacitor 20 in
the second embodiment receives the reference voltage Vc1, and the
second terminal 25 is electrically coupled to the second terminal
15 of the light-sensing component 10.
[0035] It should be noted that, in the second embodiment, the third
control signal Sn+1 received by the third terminal of the
light-sensing component 10 is in the low level (e.g., from -6 volts
to -16 volts), which is opposite to that of the first embodiment.
When the voltage difference .DELTA.V of the variable capacitor 20
is increased, the capacitance of the variable capacitor 20 is
decreased. When the voltage difference .DELTA.V of the variable
capacitor 20 is decreased, the capacitance of the variable
capacitor 20 is increased. Connection relationships of other
components in the second embodiment are same to those of the first
embodiment, which will not be repeated herein.
[0036] FIG. 6 is a timing-sequence view of the second exemplary
embodiment of the present disclosure. Referring to FIG. 5 and FIG.
6 together, the following will describe an operation principle of
the self-adjusting photosensitive touch circuit 110, and an
operation process of the self-adjusting photosensitive touch
circuit 110 can be divided into a reading-out stage, a resetting
stage, and a sensing stage.
[0037] Firstly, in the reading-out stage, when the second control
signal Gn is in the high level, the switch component 30 is turned
on, the voltage Va0 of the first terminal 23 of the variable
capacitor 20 is decreased to the first voltage value Va1 with
time.
[0038] In the resetting stage, when the first control signal Gn+1
is in the high level, the third control signal Sn+1 are in the low
stage and the second control signal Gn is in the low level, the
switch component 30 is turned off, the light-sensing component 10
is turned on, and the voltage Va0 is decreased from the first
voltage value Va1 to the second voltage value Va2 with time. In
addition, when the first control signal Gn+1 is in the high level
and the third control signal Sn+1 is in the low level, a rising
edge of the first control signal Gn+1 and a falling edge of the
third control signal Sn+1 are behind a rising edge of the second
control signal Gn.
[0039] In the sensing stage, when the first control signal Gn+1 and
the third control signal Sn+1 are in the low level, and the second
control signal Gn is in the low level, the switch component 30 is
turned off and the light-sensing component 10 is turned off, the
gate voltage Vgs of the light-sensing component 10 is equal to a
value that the low level of the first control signal Gn+1 subtracts
the voltage Va0. Thus, the voltage Va0 increases from the second
voltage value Va2 with time.
[0040] Then, return back to the reading-out stage, when the second
control signal Gn is in the high level again, the switch component
30 is turned on, and the voltage Va0 of the first terminal 23 of
the variable capacitor 20 is increased to the first voltage value
Va1 with time.
[0041] Therefore, when there is no light irradiation, the voltage
Va0 is decreased to cause the voltage difference .DELTA.V is
increased, the capacitance of the variable capacitor 20 is
automatically decreased, so that the charge stored in the variable
capacitor 20 becomes less. The voltage difference .DELTA.V is equal
to a value that the reference voltage Vc1 subtracts the voltage
Va0. Then, when the second control signal Gn is in the high level
again, the integrator 150 (as shown in FIG. 9) judges the touch
status according to a relationship between the voltage Va0 and the
reference voltage Vref. In detail, when the voltage Va0 is not
greater than the reference voltage Vref, the touch status is no
touch.
[0042] When the light irradiates with the high intensity, the
voltage Va0 is increased to cause the voltage difference .DELTA.V
is decreased, the capacitance of the variable capacitor 20 is
automatically increased, so that the charge stored in the variable
capacitor 20 becomes greater. Finally, when the second control
signal Gn is in the high level again, the integrator 150 (as shown
in FIG. 9) judges the touch status according to a relationship
between the current voltage Va0 and the reference voltage Vref. In
detail, when the voltage Va0 is greater than the reference voltage
Vref and is equal to a preset voltage value, it judges the touch
status is having touch. The reference voltage Vref is less than the
preset voltage value.
[0043] FIG. 7A is another curve diagram of the output voltage
difference and the gate voltage of a conventional technology. FIG.
7B is a curve diagram of the output voltage difference and the gate
voltages of the second exemplary embodiment of the present
disclosure. Referring to FIG. 7A, the conventional technology uses
a capacitor with a fixed capacitance, the gate voltage Vgs of the
light-sensing component 10 is in a range from about 0 volt to 4
volts. Referring to FIG. 7B, after using the variable capacitor 20
of the second embodiment of the present disclosure, the third
terminal 17 of the light-sensing component 10 receives a low level
(e.g., from -6 volts to -16 volts) of the third control signal
Sn+1. The gate voltage Vgs of the light-sensing component 10 is in
a range from about 2 volts to -10 volts. Therefore, an operational
range of the light-sensing component 10 is approximately 3 times
that of the light-sensing component of the conventional technology.
It should be noted that, due to the operational range of the
light-sensing component 10 being increased, the present disclosure
will decrease the misjudgment probability of the light-sensing
component 10, and improve the sensitivity and accuracy of the
light-sensing component 10.
[0044] FIG. 8 is a structure schematic view of a variable capacitor
in accordance with an exemplary embodiment of the present
disclosure. Referring to FIG. 8, the variable capacitor 20 has a
vertical stack structure. The variable capacitor 20 can be made by
a physical vapor deposition (PVD) process or a chemical vapor
deposition (CVD) process. The variable capacitor 20 includes a
metal layer 201, a semiconductor layer 203, an insulating layer 205
(or is called as an oxide layer), and a metal layer 207.
[0045] In general, carriers in the semiconductor layer 203 can
migrate with the applied voltage, which causes interface between
the insulating layer 205 and the semiconductor layer 203 to occur
carrier accumulation, depletion, or reversal phenomenon, thereby
affecting the capacitance of the variable capacitor 20. In
addition, in another embodiment of the present disclosure, the
metal layer 201 can be omitted.
[0046] It should be noted that, because the variable capacitor 20
has a simple structure, and is easy to be produced, so that the
process of the original touch display device will not be affected.
In other words, the self-adjusting photosensitive touch circuit in
accordance with the embodiments of the present disclosure does not
affect the yield and productivity of the original touch display
device, but it can improve the sensitivity and accuracy of the
touch display device.
[0047] FIG. 9 is a partial circuit block diagram of a display
device in accordance with an exemplary embodiment of the present
disclosure. Referring to FIG. 9, the display device 900 includes at
least one scanning line, at least one data line, a display pixel
unit 130, a display pixel unit 131, a self-adjusting photosensitive
touch circuit 100, a self-adjusting photosensitive touch circuit
101, and an integrator 150.
[0048] The display pixel unit 130 is electrically coupled to the
scanning line and the data line, respectively. The display pixel
unit 130 includes a thin film transistor Q1, a liquid crystal
capacitor C1, and a storage capacitor C2. A gate of the thin film
transistor Q1 is electrically coupled to the scanning line which is
in the horizontal direction, a source of the thin film transistor
Q1 is electrically coupled to the data line which is in the
vertical direction, and a drain of the thin film transistor Q1 is
electrically coupled to one terminal of the liquid crystal
capacitor C1 and one terminal of the storage capacitor C2.
[0049] When a sufficient voltage is applied on the scanning line in
the horizontal direction, the thin film transistor Q1 which is
electrically coupled to the scanning line can be turned on. At the
moment, the drain of the thin film transistor Q1 can be
electrically coupled to the data line in the vertical direction. So
that, a video-signal voltage of the data line can be written into
the liquid crystal capacitor C1 and the storage capacitor C2 of the
display pixel unit 130, thereby, thereby, it can control light
transmittance of different liquid crystal (not shown) to achieve a
control color effect.
[0050] The self-adjusting photosensitive touch circuit 100 includes
a light-sensing component 10, a variable capacitor 20 and a switch
component 30. A source of the switch component 30 is electrically
coupled to the data line (or is called as a readout line). One
terminal of the data line is coupled to a first terminal of an
operational amplifier OP in the integrator 150. A capacitor Cfb and
a multiplexer Mux are electrically coupled in parallel between the
first terminal of the operational amplifier OP and an output
terminal of the operational amplifier OP. A second terminal of the
operational amplifier OP receives the reference voltage Vref.
[0051] When there is no light irradiation, and a sufficient voltage
is applied on the scanning line, the switch component 30 is turned
on, the voltage Va0 of one terminal of the variable capacitor 20
can be set to be equal to the reference voltage Vref. Then, when
the first control signal Gn+1 and the third control signal Sn+1 are
in the high level, and the scanning line (or the second control
signal Gn) is in the low level, the switch component 30 is turned
off, the light-sensing component 10 is turned on. When the first
control signal Gn+1 and the third control signal Sn+1 are in the
low level, and the scanning line (or the second control signal Gn)
is in the low level, the switch component 30 and the light-sensing
component 10 are turned off.
[0052] Due to no light irradiation, the voltage Va0 is great to
cause the voltage difference .DELTA.V small, the capacitance of the
variable capacitor 20 is automatically decreased, so that the
charge stored in the variable capacitor 20 becomes less. When the
scanning line (or the second control signal Gn) is in the high
level again, the switch component 30 is turned on. The integrator
150 judges the touch status is no touch according to the amount of
the integrated charges, and outputs a voltage Vout corresponding to
the touch status with no touch.
[0053] When the light irradiates with the high intensity, the
voltage Va0 is small to cause the voltage difference .DELTA.V
great, the capacitance of the variable capacitor 20 is
automatically increased, so that the charge stored in the variable
capacitor 20 becomes greater. In other words, when light
irradiation intensity received by the light-sensing component 10 is
greater, the capacitance of the variable capacitor 20 is greater.
When the scanning line (or the second control signal Gn) is in the
high level again, the switch component 30 is turned on. The
integrator 150 judges the touch status is having the touch
according to the amount of the integrated charges, and outputs a
voltage Vout corresponding to the touch status having the
touch.
[0054] It should be noted that, the judgment of the touch results
in the embodiments of the present disclosure takes the light pen
operation modes as an example. If operating by the finger, the
judgment of the touch control results is opposite to that of the
touch results when using the light pen.
[0055] Similarly, the display pixel unit 131 can have the same
circuit structure and operation principle as the display pixel unit
130. The self-adjusting photosensitive touch circuit 101 can have
the same circuit structure and operation principle as the
self-adjusting photosensitive touch circuit 100, which will not be
described herein. In addition, if considering other designs, the
embodiments of the present disclosure can omit the integrator
150.
[0056] In summary, the self-adjusting photosensitive touch circuit
and the display device of the present disclosure uses the
characteristics of the variable capacitor which can automatically
adjust the capacitance thereof. When there is no light irradiation
on the touch circuit, the variable capacitor automatically changes
to have a small capacitance, so that the stored charge is small.
When there is light irradiation on the touch circuit, the variable
capacitor changes to a large capacitance, so that the stored charge
is great, thereby making a charge difference between the light
irradiation condition and no light irradiation condition be
greater. In other words, the range of the gate voltage difference
of the light-sensing component can be increased, so as to improve
sensitivity and accuracy of the light-sensing component and the
touch display device thereof.
[0057] The above description is given by way of example, and not
limitation. Given the above disclosure, one skilled in the art
could devise variations that are within the scope and spirit of the
disclosure disclosed herein, including configurations ways of the
recessed portions and materials and/or designs of the attaching
structures. Further, the various features of the embodiments
disclosed herein can be used alone, or in varying combinations with
each other and are not intended to be limited to the specific
combination described herein. Thus, the scope of the claims is not
to be limited by the illustrated embodiments.
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